Thermo-electric generator.



H. W. WEBB.

THERMO ELECTRIC GENERATOR.

APPLICATION FILED MAR. 11. 191a.

1,242,499. Patented Oct. 9,1917.

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THEBMO ELECTRIC GENERATOR.

APPLICATION FILED MAR. I7. 1913.

1,242,499. Patented Oct. 9,1917.

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APPLICATION FILED MAR.17. I913- Patented 'Oct. 9, 1917.

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m'rwnnr. w. WEBB, OF OBESSKILL, NEW JERSEY.

To all whom it may concern:

Be it known that I, HARTWELL W. WEBB, a citizen of the United States, and resident of Cresskill, in the county of Bergen and tion is to produce a thermo-electric generator which is particularly adapted for utisuch a device.

lizing the waste heat of the exhaust gases of internal combustion engines, although not limited to that use.

Another object of the invention is to provide a comparatively inexpensive and durable generator possessing a high efliciency of transformation, and one which is simple in construction so as to be capable of manufacture on a commercial scale, or in other words which is not so difiicult to manufacture as to be beyond the reasonable cost of A further object 'of the invention is to produce a joint or junction between the elements of the generator which will effectively withstand the changes in temperature, and which is in no way aifected by the varying rates of thermal expansion of the dissimilar metals or alloys forming the thermo-electric couple, that is to say two adjoining elements of the generator.

A still further object of the invention is to provide the generator with an automatic electric potential regulating means, such regulating means serving at the same time to increase the efliciency of the transformation of energy. a

With these and other objects in view, which will more fully appear as the nature of the invention is better understood, the same consists in the combination, arrangement and construction of parts hereinafter fully described, pointed out in the appended claims and illustrated in the accompanying drawings, it being understood that many changes may be made in the size and proportion of the several parts and details of construction within the scope of the a pended claims without departing from t e Specification of Letters Patent.

Application filed Harsh 17, 1918. Serial No. 754,912.

THEBMO-ELECTBIG GENERATOR.

Patented Oct. 9, 1917.

spirit or sacrificing any of the advantages of the invention.

A few of the many ossible embodiments of the invention are 1 ustrated in the accompanying drawings, in which Figure 1 is a front elevation of one of the elements of a generator constructed in accordance with the present invention; Fig. 2 is a side elevation thereof; Fig. 3 is a front elevation of a modified element; Fig. 4 is a side elevation of this modified element; Fig. 5 is an elevation, partly in section, of a generator constructed in accordance with this invention; Fig. 6 is a front elevation of another modified element; Fig. 7 is a side elevation thereof; Fig. 8 is a front elevation of a further modification and Fig. 9 is a side elevation of the same; Fig. 10 is an elevation, partly in section, of a portion of a generator built of elements shown in Figs. 6 and 7; Fig. 11 is a front elevation of a further modification of an element; Fig. 12 is a'front elevation of an insulating block to be disposed between such elements; Fig. 13 is a side elevation of the said insulating block; Fig. 14 is an elevation of a portion of a generator, partly in section, constructed of elements shown in Figs. 11 to 13, inclusive; Fig. 15 is a front elevation of a detail of construction of the generator shown in Fig. 14; Fig. 16 is a front elevation of a further modification'of an element; Fig. 17 is a front elevation of the insulating material to be used between the elements shown in Fig. 16;

Fig. 18 is a side elevation of the insulating material shown in Fig. 17; Fig; 19 is a plan view of a generator constructed of elements shown in Figs. 16 to 18, inclusive; Fig. 20 is a section taken on line 20-20 of Fig. 19; Fig. 21 is a plan view of an internal combustion engine with a generator in position thereon; and Fig. 22 is also a plan view of an internal combustion engine with a modified generator mounted thereon.

In forming thermo-electrio couples, that is to say in joining two adjacent elements of a thermo-electric generator, difiiculties have been experienced heretofore owing to the fact that the unlike materials, forming the couple, have difi'erent rates of thermal expansion. Joints formed by soldering or brazing are apt to be, and in fact are often,

loosened, thereby reducing to a great extent the elficiency of the. generator. To. obviate these -=defectsgfithe generators, forming the subject inatter' of the present application for Letters Patent, comprise thermo-electric couples having, for instance, ironas the 7 positive elements, and an alloy of nickel .rials are used.

tric spotweldbetween iron, for instance Norway iron, and an alloy of nickel and copper is so intimate that the iron acquires the color, of the alloy at the point opposite the weld- The thermal conductlvity of'the 'ironbeing considerably greater than that of the nickel and copper. alloy, the iron element is formed of a smaller cross section than the nickel copper element, to compensate for the difl'erence between their unlike thermal conductivities. The same rule must betaken into consideration if other mate- Referring now to the drawings, each couple consistsv of, two elements and 31,

composed of unlike metals for instance of those above referred to, and joined together by electric spot welding, or in any other suitable manner Each element consists of .a ,strip,,. the inner end of which, that is to sayijthat end which is to be heated, is greatly reduced in size. .To form a generator unit of joined couples and to hold the elements .in place, asuitable impervious heat conduct .ing and electric insulating bmdmg material is j1 sed,;for instance a cement of as great a thermal conductivity as is conslstent Iwith nasmuch as the nickel-copper alloy, is expensive,

the elements are, preferably, formed by punching them from atape without waste, and while it is not essential to the operation of-the generator that both elements of a couple should be of the same or similar shape, they are, preferably, made of the same width and approximately ofthe same length andshape, in order to reduce the cost In Figs. 1 and 2 an element of a couple is shown, comprising a strip 32 having aninner reduced end 33. In forming this reduced end, the outer end .of the next strip. stamped from the tape is slotted, as clearly shown at 34. If the elements are. stamped from a sheet and the saving of mater al does not enterinto consideration, the slot 34 n'eed not be formed, although, to produce a better cooling effect on the outer ends of the couples, such slot orbreak is preferably formed. To hold the binding material firmly in place, and to reinforce the latter*againstinternal pressure, that portion of the 32which is means of which the electric the elements, rods 51, over which embedded in the binding material may be roughened, as shown at 35, on one or bothof its sides, orgthe strip maybe slit, as shownat 36, 36 in Fig.3 of the drawings, and the portions of the metal between the slits may be bent in different planes, as indicated-at 37. Other reinforcing means may be provided, for instance the form shown 'like configuration by a binding heat conducting and electric insulating material 40,v for instance cement. This binding material forms a ring-like structure, in which portions of the elements of the. generator are embedded, their reduced ends 33 projecting throughout their lengths into said ring, and their outer ends being exposed to air. To strengthen the binding mass, a ringof interwoven asbestos and wirenetting 41 is placed upon both sides thereof, such ring increasing at the same time the heat conductlvity of the binding material- If the generator is to comprise more than one of the units now described, such units are bolted together by screws 43, l3, the ter- 'minals of the units being electrically connected by wires 44, and the terminals of the entlre generator provided with conductors 45, WhlCh are connected to the device by translated.

Ifabinding material of high thermal con-. ductivity is used, for instance metal, sleeves 46 of asbestos or like substance are drawn over the, elements, 7 of the drawings, said sleeves being then embedded in the binding material 40, as shown in the form illustrated in Fig. 10 of the drawings. Instead of asbestos, obviously other electric insulating material may be used just as well.

The chains of couples may be arranged in straight lines, as shown in Figs. and 20. The strips, constituting ments of the device shown in F1 notched at their edges, as indicate 1n Fig. 11, the insulating blocks 48 between the elements being provided with notches, 49, the latter registering with thosein the str1ps. 'A chain of. these couples with the insulatmg blocks disposed between the elements thereof is formed, sheets 50 of insulatmg material are placed upon the sides of insulating sleeves 52 are drawn, are seated in the notches in the strips and insulating blocks,

the ele- 14, are at 47, 47

energy is to be as shown in Figs. 6 and' the chain placed upon a support and clamped together by any suitable means,

after which insulating sheets 53 are attached by cement, or otherwise, to the sides of the unit to cover the rods 51. Instead of providing notches in the edges of the strips, apertures 54 may be formed in the body portions thereof, as shown in Fig. 16 of the drawings, the insulating blocks 55 having also apertures, denoted by the numeral 56, in registering positions with the apertures 54. A generator composed of these elements is shown in Figs. '19 and 20, comprising three units 57, 58 and 59. These units are attached to angle-irons 60, held upon a base plate 61. The means for attaching the units to the angle-irons 60 and for formi the said units comprise screw bolts 60', over which are drawn insulating sleeves 62, said screw bolts being seated in the apertures 54 and 56 and holes 63 in the angleirons 60, clamping nuts 64 meshing with the threads of the screw bolts. The terminals of the units are electrically connected by conductors 65, the binding posts of the terminals being indicated by the numerals 66, 66. Between the units are disposed longitudinally insulating strips 55. p

The generators now described are mounted in the path of the exhaust gases upon internal combustion engines as close as possible to the exhaust ports thereof. Obviously they may be combined with other heating devices just as well.. Fig. 21 of the drawings illustrates an internal combustion engine, having mounted thereon a generator of the ring type. The cylinders of the engine are denoted bythe numerals 67, the exhaust ports being shown at 68. An exhaust pipe 69, commonto all of said exhaust portsis provided, said pipe having flanges in alinementwith flanges 71' upon the cylinders. The'generator is placed between these flanges and fastened thereto by means of the bolts 43 above described.

' In the device shown in Fig. 22 a generator of the, straight type is shown mounted upon an internal combustion engine, denoted by the numeral 71.- The generator forms in this case the front wall of the exhaust manifold 72, screw bolts 73, which might be identical with the rods 51 or 60 above described, serving to make the union between the top and bottom of the manifold 72 and the generator. Electric insulators Z4, in the form of strips, are inserted between the generator and the top and-bottom "of themanifold 72. Considering the operation of the devices shown in Figs. 21 and 22, it is to be observed that the inner reduced ends of the elements are exposed throughout their lengths to the heat of the products of combustion passing through the-exhaust pipe or manifold. That fraction of the heat which is gathered by the binding means is wasted through the mass of metals in contact therewith, that is to say through the engine and the exhaust pipe or manifold. That fraction which is received by the couples is divided into two parts, namely one which travels by thermal conduction to the binding means in part and in part to the cooling junctions, that is to say the outer ends of the couples and tends to decrease the efliciency of the transformation of energy, and the other and lesser part which 'mamtains the heat at the inner junctions and is absorbed, so to say, and transformed into electric energy. It is to be observed that the highest electromotive force is set up or generated when the fall in the thermic potential between the heated and she coohng junctionsis as great'as possible. The binding"'nia.ss"being arranged at a point intermediate between the heated and cooling junctions and in thermal communication with an external mass, that is to say the exhaust manifold Which operates in conjunction with the engine frame as a thermal sump, a great fall in thermic potential between the heated and cooled junctions is obtained. Inasmuch as, however, the temperature of this thermal sump is substantially even, the electric potential of the generator is maintained at substantially the same point. The width of the elements, where embedded in the binding mass or insulating material, respectively, 1s enlarged, whereby an increased flow of heat to the sump is obtained. The purpose of reducing the size of the junctions which are exposed to heat is to maintain the said junctions at the hi hest temperature attainable. Since the friction of the hot gas stream is the vehicle by which convection takes place between the products of combustion and the junctions, a construction is employed, 5. 6., an open comb structure, which gives the greatest possible frictional resistance to the gas stream without choln'ng the motor at high speeds if the device is mounted upon internal combustion engines, or without unduly diminishing the velocity of the gas where the invention is otherwise employed. Since it is preferable to reduce the lengths of the heated junctions in order to lessen the internal resistance of the generator, the device is located as near as possible the outlets of the cylinders. The exhaust gases metallic positive element and a ative element, the corresponding ends of said the cooled junctions of the couples are slotted, as above described, a broken surface will be presented to the air currents produced by the fan, such surface offerin more resistance to the air at a high speed than an unbroken surface and the lessened direct radiation of heat by said broken surface is more than counterbalanced by the increased convection.

What I claim is 1. A thermo-electric couple,

comprising a metallic ne elements being reduced in size, said reduced ends constituting throughout their lengths the joint to be heated, the other ends of said elements having breaks.

2. A thermo-electric couple, comprising a metallic positive element and a metallic neg. ative element, the corresponding ends of said elements being reduced in size, said reduced ends constituting throughout their lengths the joint to be heated, a portion of the surface of each element immediately beyond its reduced end being uneven and having the same resistance as the even portion thereof, and the free ends .of said elements having breaks.

a 3. In a thermo-electric generator, the combination with a refractory wall, of thermoelectric couples passing through said wall, one end of each element of each couple being reduced in size, said reduced ends projecting throughout their lengths beyond one surface of said wall and constituting the joints to be heated, and those portions of the elements which are embedded in said wall being uneven and having the same resistance as the even portion thereof.

4. In a thermo-electric. generator, the combination with a refractory wall, of thermoelectric couples passing through said wall, one end of each element of each cou le being reduced in size, said reduced en proj ecting throughout their lengths beyondone surface of said walland constituting the 1 joints to be heated, and the ends of the elements projecting beyond the other surface of said wall having breaks.

5. In a thermo-electric generator, the combination with a refractory "wall, of thermoelectric couples passing through said wall, one end of each element of each couple being reduced in size, said reduced endsprojecting throughout their lengths beyond one surface of said well and constituting the joints to be heated, those portions of the elements which are embedded in said wall being uneven and having the same resistance as. the even portion thereof, and the ends of the elements projecting beyond the other surface of said wall having breaks.

Signed at New York, in the county of New York and State of New York, this 17th day of February, A. D. 1913.

HARTWELL W. WEBB.

Witnesses:

SIGMUND Hnnzoe, S. BIRNBAUM. 

